Raw disk I/O

[Chris Torek]

In article <MARC.90Feb14083116 at focsys.uucp> marc at focsys.uucp (Marc H. Morin)
writes:
>I need to know a little more about the behaviour
>of the raw disk driver (in general) for BSD systems.  If it helps, I am
>particularly interested in SCSI drives on Sony and Mips workstations.

These are not `BSD systems' so much as `systems whose original source
was 4BSD'.  Both Sony and MIPS have made substantial changes to parts
of the kernel, some of which will affect raw I/O (raw I/O is tied into
the VM system, for instance).

>1) Does file locking via fcntl() still apply ?

No, because there are no files.  fcntl() does not do file locking in BSD
anyway: fnctl() for locking is a System V feature.  BSD provides only flock().

>2) I understand the disk is viewed as one single flat-file,  but does
>   this also mean that I must handle bad sectors within my application ?

No.  ECC and bad sector replacements are handled by the disk driver
(or by a software layer either above or within the driver, but in any
case, below the `raw I/O' level).
-- 
In-Real-Life: Chris Torek, Univ of MD Comp Sci Dept (+1 301 454 7163)
Domain:	chris at cs.umd.edu	Path:	uunet!mimsy!chris